Arthritis is a complaint suffered by all types of animals that have an endoskeletal supporting structure composed of bone, ligaments, and cartilage. Such animals include humans, cats, dogs, horses, and many others.
There are two major forms of arthritis. Rheumatoid arthritis is a common form of arthritis which involves inflammation of the joints, swelling, pain, and loss of function. The primary symptom of rheumatoid arthritis is inflammation of the synovial membrane. The membrane thickens and synovial fluid accumulates. The resulting pressure causes pain and tenderness.
The most common form of arthritis, osteoarthritis, is a degenerative joint disease that is far more common than rheumatoid arthritis. It is characterized by the deterioration of articular cartilage and the formation of new bone in the subchondral areas and at the margins of the joint. The cartilage slowly degenerates and as the bone ends become exposed small bumps of new osseous tissue are deposited on them. These bumps decrease the space in the bone cavity and restrict joint movement.
Both forms of arthritis are more common in older animals, although they are still found in young animals, usually due to a genetic disorder.
Arthritis in animals may also be caused by Lyme disease and primary cartilage degeneration in young dogs.
Arthritis is a slowly progressive disease that starts with almost undetectable discomfort, and may progress to the point where the animal refuses to stand, walk, or even eat. In companion pets, the pet owner may first notice the disease when the animal has slight difficulty in getting up and down, climbing stairs, jumping up on furniture or into cars, soreness hours after exercise, or grumpiness.
Non-steroidal anti-inflammatory agents (NSAIDs) such as aspirin, ibuprofen, ketoprofen and naproxen, are effective in reducing arthritic pain. NSAIDs relieve pain by acting on the cyclooxygenase portion of the enzyme prostaglandin synthase. Two isoforms of cyclooxygenase exist, cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Both isoforms catalyze the reaction that converts arachidonic acid into a class of hormones known as eicosinoids, which include prostaglandins, prostacyclins, and thromboxanes. COX-1 is expressed in all mammalian tissues, and serves a variety of homeostatic physiologic functions. It is responsible for the production of protective prostaglandins in the kidney and the stomach, as well as the functional thromboxane of platelets. In contrast, COX-2 is not normally found in most tissues, and is expressed under conditions of tissue damage. COX-2 leads to the biosynthesis of prostaglandins, triggering pain and inflammatory responses.
The inhibition of COX-2 is critical to the anti-inflammatory effects of NSAIDs, while the vast majority of side effects can be linked to the inhibition of COX-1. Typical side effects of NSAIDs include abdominal pain, diarrhea, vomiting, stomach and intestinal ulcers, kidney and liver damage, and decreased blood clotting. Drugs that selectively target the COX-2 enzyme can be expected to maintain clinical efficacy with a reduction in side effects.
Coxib drugs are compounds which target the inhibition of the inducible enzyme COX-2 while sparing the activity of COX-1. Currently available Coxib drugs in human medicine include Vioxx® (rofecoxib) and Celebrex® (celecoxib). Duramaxx® (deracoxib) is currently the only Coxib drug approved for veterinary use.
There is therefore a continuing need in the art for the development of medications that are COX-2 selective for treating inflammation and pain in animals.
Accordingly, it is a primary objective of the present invention to provide a composition and method for treating arthritis and other inflammatory disorders in animals, especially companion animals, using a COX-2 selective inhibitor.
It is a further objective of the present invention to provide a composition and method for treating inflammatory disorders in animals that is derived from blue-green algae.
It is still a further objective of the present invention to provide a composition and method for treating inflammatory disorders in animals that is less toxic and has fewer side effects than COX-1 inhibitors.
It is yet a further objective of the present invention to provide a composition and method for treating inflammatory disorders in animals that is palatable and easy to administer.
It is a further objective of the present invention to provide a composition and method for treating inflammatory disorders in animals that is orally active.
The method and means of accomplishing each of the above objectives as well as others will become apparent from the detailed description of the invention which follows hereafter.